<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- 获得字符串第 N 个位置的字符 -->
    <script>
        var Cut = prompt('判断你输入某个字符的下表出现的位置')
        var arr = 'akfsgaoigwfiuawgfbasiufbaskjbfajhwgf';
        for(var i = 0 ; i<arr.length ; i++){
            alert(arr.charAt(Cut))
            break;
        }
         
    </script>
</body>
</html>